Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
http://www.youtube.com/watch?v=qxb2_d9ilEw Excretory & Nervous Systems • Regulation within animal systems requires maintaining homeostasis- the ability of the body or a cell to seek and maintain stability within its internal environment when dealing with external changes • There are several organ systems that work together to maintain an organism’s internal environment, despite changes that occur in its external environment. • The nervous system maintains homeostasis by controlling and regulating the other parts of the body. • The excretory system helps regulate the concentration of water and other components of body fluids. Homeostasis – Every organ system plays a role in maintaining the constancy of the internal environment. – Examples: • Blood level of nutrients, blood pressure, heart activity, wastes must not be allowed to accumulate, body temperature must stay within normal limits Homeostatic Control Mechanisms • Communication within the body is essential for homeostasis. • Homeostasis is accomplished primarily by: 1. Endocrine system (blood borne hormones) 2. Nervous system (electrical signals) Negative Feedback vs. Positive Feedback Mechanisms Negative Feedback Mechanism – The net effect of the response to the stimulus is to shut off the original stimulus or to reduce its intensity. – Examples: Thermostat or body temperature, heart rate, blood pressure, breathing rate, blood levels Positive Feedback Mechanism – Feedback that tends to cause a variable to change in the same direction as the initial change; enhances the stimulus – Examples: Blood clotting, birth of a baby – More rare in the body Excretion – the process by which metabolic wastes are eliminated from the blood One part of the many processes that maintain homeostasis. Every cell in the body produces metabolic wastes, such as excess salts, carbon dioxide, and urea The Excretory System Maintains Homeostasis In 3 Steps: 1. Filtration- Filters substances from the blood 2. Reabsorption- Regulate the chemical composition of body fluids by retaining the proper amounts of water, salts, and nutrients 3. Secretion- Elimination of wastes in the form of urine Evolutionary Trends in Excretion Complex Simple Animal Aquatic Worms and Taxon Invertebrates Mollusks Release Wastes By… diffusion to remove waste across their cell membranes directly into the water Use of nephridia- tiny pores along the body excrete wasste Insects Using malpighian tubules to collect and excrete wastes Vertebrates Use of kidneys, ureters, and a bladder to collect and excrete waste Picture of system Examples Sponges, jellyfish, Earthworm, clam, Grasshopper, ants, planaria octopus bees mammals, birds, reptiles, fish, amphibians 1. Kidneys 1. Renal artery 2. Renal Vein 2. 3. 4. Ureters Urinary Bladder Urethra Kidneys (renal = kidney) Located on either side of the spinal column near the lower back. Paired organs that receive blood via the renal artery The main filtering units are tissues called nephrons that separate the components of the blood Every 45 minutes kidneys filter all the blood in your body Excess water and urea in the form of urine leave the kidney via the ureter where it leaves as urine out the urethra Filtered blood leaves kidneys and returns to circulation carrying nutrients, salts, and water via the renal vein A tube, called the ureter, leaves each kidney carrying urine to the urinary bladder The urinary bladder is a saclike organ where urine (a mixture of urea, water, and salt) is stored before being excreted. Foley Catheter Tube that carries urine from bladder to the outside of the body Levels of Organization Renal cells, bladder cells, etc… Nephrons Kidneys, Bladder, Ureter, Urethra Excretory Sometimes substances such as calcium, magnesium, or uric acid salts in the urine crystallize and form kidney stones. When kidney stones block the ureter they cause great pain. Often treated using ultrasound, in which the sound waves pulverize the stones into smaller fragments Prevent by: drink lots of water, diet lower in protein (N), sodium Antidiuretic Hormone Hypothalamus | Tells pituitary that amount of water in blood is low. Low amounts of water in blood and high amounts of urine produced Tells pituitary that amount of water in blood is high. Pituitary Stops releasing ADH into bloodstream | Releases ADH into bloodstream Kidneys Reabsorbs more water. | Reabsorbs less water. High amounts of water in blood and low amount of urine produced. Lungs of the respiratory system remove CO2 from blood. The circulatory system brings wastes to the lungs, kidneys, and skin for excretion. Skin of the integumentary system excretes water, urea, salts, and other wastes through sweat. Humans have two kidneys and can survive with only one. If both kidneys are damaged by disease or injury, there are two ways to keep an individual alive. 1. Kidney Transplant 2. Kidney Dialysis Machine ▪ Expensive ▪ Time consuming (3 X /week for few hours)